One million Japanese children every year learn the abacus, which they call soroban.
The high point of the abacus calendar is the All Japan Soroban Championship, which took place earlier this year in Kyoto.
And the high point of the championship is the category called "Flash Anzan" – which does not require an abacus at all.
Or rather, it requires contestants to use the mental image of an abacus. Since when you get very good at the abacus it is possible to calculate simply by imagining one.